Photodetectors are used to detect or sense light or other electromagnetic energy. Currently available photodetectors are generally used in a variety of practical applications such as wired and wireless communications, sensing, monitoring, scientific instrumentations, national security, and so on.
Many optical photodetectors use semiconductor materials as the photodetection material system. Semiconductor materials, however, have a band gap, and therefore only photons having energy greater than the band gap can be detected, potentially leaving photons undetected. In addition, the intrinsic bandwidth of semiconductor based photodetectors is limited by the carrier transit time in the photodetection region. Both of these limitations results in a less than optimal photodetector.